1. Field of Invention
The present invention relates generally to the field of waveguides. More specifically, the present invention is related to guidance mechanisms for waveguiding of Surface Plasmons.
2. Discussion of Prior Art
Guiding light through air has always been a challenging goal in the world of optics, and special techniques have always been necessary to achieve it, since in the presence of dielectric media light tends to localize itself mostly in the high-refractive-index regions. For all-dielectric structures, a photonic bandgap (as described by Joannopoulos et al. in the publication titled “Photonic Crystals: Molding the Flow of Light”) is the only mechanism that can rigorously succeed in guiding most of the field in the low-index medium, since other demonstrated methods based on index guiding (such as the method described in the paper to Xu et al. titled “Experimental Demonstration of Guiding and Confining Light in Nanometer-Size Low-Refractive-Index Material”) work only provided that the high-index regions do not extend to infinity.
Including conducting materials, one can also explore surface-plasmon modes (as described in the publication to Raether titled “Surface Plasmons”) to guide light. Since for these modes the field stays attached to the surface of the conductor, the most common method employed so far to create transversely localized guided modes has been to close this surface onto itself, namely by using a conductor with a finite cross-section (as described in: (1) the paper to Takahara et al. titled “Guiding of a One-Dimensional Optical Beam With Nanometer Diameter”; (2) the paper to Berini et al. titled “Plasmon-Polariton Waves Guided by a Metal Film of Finite Width by Different Dielectrics”; (3) the paper to Weeber et al. titled “Optical Near-Field Distributions of Surface Plasmon Waveguide Modes”; (4) the paper to Nikolajsen et al. titled “Polymer-Based Surface-Plasmon-Polariton Stripe Waveguides at Telecommunication Wavelengths”; and (5) the paper to Hochberg et al. titled “Integrated Plasmon and Dielectric Waveguides”). Other suggestions have been to combine surface plasmons with bandgaps by corrugation of the metal for confinement in different directions (as described in the paper to Bozhevolnyi et al. titled “Waveguiding in Surface Plasmon Polariton Band Gap Structures”) or to use coupled-metallic-nanoparticle chains as plasmon waveguides (as described in the paper to Maier et al. titled “Local Detection of Electromagnetic Energy Transport Below the Diffraction Limit in Metal Nanoparticle Plasmon Waveguides”).
Whatever the precise merits, features, and advantages of the above mentioned techniques, none of them achieves or fulfills the purposes of the present invention.